Apparatus for segregating foreign matter from smokable material

ABSTRACT

Particles of non-smokable material are segregated from a flow of a mixture of smokable and non-smokable materials by subjecting the flow to a first segregating treatment which divides the flow into a first stream consisting practically exclusively of smokable material, and a second stream constituting a relatively small percentage of the flow and containing substantially all of the non-smokable material and the remnant of smokable material. The second stream is treated for a second time, preferably at the discharge end of a pneumatic conveyor system including at least one conduit, to segregate the non-smokable material from the remnant of smokable material which latter can be admitted to the first stream. The segregating device which divides the flow into the first and second streams is or can be utilized to treat the second stream, i.e., to segregate smokable material of the second stream from the non-smokable material of the second stream.

CROSS-REFERENCE TO RELATED CASES

This application claims the priority of the commonly owned copending European patent application EP 03 022 094.1 filed Oct. 2, 2003.

The disclosure of the above-referenced European patent application, as well as of all other patent applications, patents and other publications identified in the specification of the present application, are incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to improvements in methods of and in machines for treating comminuted smokable materials prior to conversion of such materials into rod-like components (called fillers) of plain or filter cigarettes, cigars, cigarillos or the like. More particularly, the invention relates to improvements in apparatus for treating mixtures of smokable material (such as shredded tobacco leaf laminae) with non-smokable material, such as particles of metal, soil or the like.

It is advisable to segregate at least some (but preferably a high percentage) of the non-smokable material from the remaining (smokable) material at an early stage of treatment of comminuted smokable material because this contributes to the quality of smokable products and simplifies the conversion of (pure or practically pure) smokable material into rod-shaped fillers of smokers' products.

It is already known to examine comminuted smokable material prior to conversion into a rod-like filler. The apparatus which serve such purpose are often called scanning devices or scanners. In accordance with one presently known proposal, the scanning device employs an optical locating unit and a plurality of neighboring nozzles serving to discharge thin or narrow air streams for expulsion of foreign matter from the flow which contains a mixture of smokable and non-smokable materials. Such mode of expulsion or segregation of non-smokable material invariably entails expulsion of a certain percentage of smokable material, i.e., the original flow is subdivided into a first stream which consists (at least substantially) of smokable material and a second stream consisting of a mixture of smokable and non-smokable materials. As a rule, or in many instances, the second stream (also called contaminated tobacco reject) contains about 1% of smokable material which was part of the original flow. Such second stream is returned into the original flow upstream of the nozzles so that it undergoes a second scanning or segregating action. This is intended to increase the percentage of smokable material forming the first stream.

The conveyor system which is employed in the just described conventional segregating apparatus to deliver the original flow to the segregating station also serves to transport the first stream from the segregating station. Furthermore, the conveyor system which returns the second stream into the original flow can contain several (such as three) belt conveyors which together form a substantially U-shaped transporting system serving to deliver the second stream into the original flow (i.e., into the mixture of smokable and non-smokable materials).

German patent application Serial No. 43 25 838 A1 discloses a modified apparatus for segregating non-smokable material from a flow of a mixture of smokable and non-smokable materials. The system which transports the second stream (containing the major part of non-smokable material) comprises two conveyors which are disposed one behind the other and are driven at different speeds. The slower upstream conveyor includes or constitutes a downwardly sloping vibratory chute. The faster downstream conveyor employs conveyor belts the upper sides or the undersides of which are arranged to transport the second stream from the vibratory chute to the original flow upstream of the segregating station.

A further apparatus for segregating smokable material from a flow containing a mixture of randomly distributed smokable and non-smokable materials is disclosed in German patent No. 0 588 543 A1. This apparatus comprises three stages. The first stage receives a mixture of shredded tobacco leaf laminae and non-smokable material; the second stage segregates smaller tobacco shreds from larger shreds; and the third stage is set up to separate tobacco shreds from non-smokable material or materials.

OBJECTS OF THE INVENTION

An object of this invention is to provide an apparatus which can segregate non-smokable material from a mixture of smokable and non-smokable materials in a space-saving manner and with a high degree of efficiency and reliability.

Another object of the invention is to provide an apparatus wherein the stream of non-smokable material which is segregated from a flow containing smokable and non-smokable materials can be manipulated in a highly efficient manner with substantial savings in (such as practically complete recovery of) smokable material.

A further object of the instant invention is to provide a novel and improved system of conveyor means for use in the above outlined apparatus.

An additional object of the invention is to provide a novel and improved method of segregating smokable material from a mixture which consists primarily of non-smokable material.

Still another object of the invention is to provide an apparatus which can be readily combined with and/or incorporated into machines for the making of a mixture of smokable and non-smokable materials.

A further object of the invention is to provide an apparatus which renders it possible to produce plain or filter cigarettes, cigars, cigarillos or other rod-shaped smokers' products wherein the rod-shaped filler is at least substantially devoid of non-smokable materials.

Another object of the invention is to provide an apparatus of the above outlined character wherein certain component parts can perform plural functions with attendant savings in space and the number of constituents, such as conveyor means for smokable and non-smokable materials and means for segregating smokable materials from non-smokable materials.

SUMMARY OF THE INVENTION

One feature of the present invention resides in the provision of an apparatus for segregating foreign matter which is randomly distributed in a flow of comminuted smokable material. The improved apparatus comprises means for advancing the flow in a predetermined direction along a first path, means for subdividing the flow in a predetermined portion of the first path into a first stream which is at least substantially devoid of foreign matter and a second stream which contains at least a major part of foreign matter and is at least likely to contain some smokable material, and means for pneumatically reintroducing—along a second path—at least some of the second stream into the first path upstream of the predetermined portion of such first path.

In accordance with a presently preferred embodiment, the reintroducing means comprises at least one pipe, hose or another tubular conveyor.

The apparatus can further comprise means for collecting the second stream downstream of the subdividing means (as seen in the predetermined direction), and means (such as a receptacle) for segregating at least some of the foreign matter from the second path prior to reintroduction of at least some of the second stream into the first path.

If the improved apparatus is arranged to segregate relatively heavy foreign matter (e.g., particles of metal or soil) from lighter material (such as fragments of tobacco ribs), the segregating means can include means for receiving the relatively heavy foreign matter by gravity flow, and the reintroducing means of such apparatus can include a suction-operated gathering device for lighter material at the collecting means. Such apparatus can further comprise a conveyor which preferably extends at least substantially transversely of the predetermined direction (of advancement of the flow) downstream of the subdividing means and is arranged to collect and advance the second stream. The discharge end of the conveyor is or can be located at the segregating means and preferably at a level above the segregating means. The conveyor can include or constitute an endless belt or an analogous endless conveyor.

The aforementioned gathering device can be arranged to draw lighter material from the stream at the collecting means, and such gathering device can be disposed at a level above the segregating means.

The aforementioned conveyor (such as an endless belt which extends at least substantially transversely of the predetermined direction downstream of the subdividing means) can be arranged to collect the second stream and to deliver the second stream to the reintroducing means.

The means for advancing the flow can comprise a vibratory trough and an endless belt or band conveyor which is arranged to receive the flow from the trough. Such advancing means can further comprise a track which is arranged to convey the at least some of the second stream to the subdividing means, and the reintroducing means can be provided with an outlet which is arranged to discharge at least some of the second stream into the track. The latter can include a partition which is disposed between the advancing means for the flow and the at least some of the second stream. Such apparatus can further comprise a receptacle which is arranged to receive the at least some of the second stream from the outlet of the reintroducing means. The just mentioned receptacle is or can be provided with an open top for reception of at least some of the second stream.

Another feature of the present invention resides in the provision of a method which can be practiced by resorting to the aforementioned apparatus or an equivalent thereof. Thus, the method includes the step of pneumatically conveying at least some of the second stream into the first path upstream of the location where the flow is subdivided into the first and second streams, and preferably also the step of subdividing the second stream into a plurality of sections prior to the subdividing step.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and the modes of assembling and operating the same, together with numerous additional important and advantageous features and attributes thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic plan view of an apparatus for segregating foreign matter from comminuted smokable material and embodying one form of the present invention; and

FIG. 2 is a front elevational view of the apparatus which is shown in FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 illustrates an apparatus which can be installed at the inlet of a cigarette rod maker, a cigarillo rod maker, a cigar rod maker or another machine for the making of rods (fillers) which are to be converted into rod-shaped smokers' products of unit length or multiple unit length. For example, the apparatus of FIG. 1 can be employed to furnish a stream of shredded tobacco leaf laminae to a machine for the making of a single continuous tobacco rod (known as filler) which is ready to be draped into a continuous web of cigarette paper and to be thereupon subdivided into plain cigarettes of unit length or multiple unit length. Reference may be had, for example, to commonly owned U.S. Pat. No. 5,135,008 granted Aug. 4, 1992 to Oesterling et al. which discloses a method of and an apparatus for making filter cigarettes and wherein pairs of plain cigarettes of unit length are united with rod-shaped filter mouthpieces of double unit length to form therewith filter cigarettes of double unit length. Such products are thereupon severed midway across the respective filter mouthpieces to yield pairs of filter cigarettes of unit length.

The apparatus of the present invention can be utilized to furnish satisfactory tobacco particles (e.g., shreds of tobacco leaf laminae or shreds which are obtained by comminuting sheets of reconstituted or substitute tobacco) to a machine for the making of a single continuous tobacco rod or to a machine for simultaneously making a plurality of continuous tobacco rods.

As a rule, a flow of comminuted smokable material contains a certain percentage of foreign matter (non-smokable material) which should be segregated from the smokable material before the latter is converted into a continuous tobacco rod which is ready for wrapping into a web of cigarette paper or other suitable wrapping material. FIG. 1 shows a flow or stream 2 of particles (e.g., shredded tobacco leaf laminae) which normally contains a relatively small percentage of foreign matter. Such foreign matter can consist of or include comminuted tobacco ribs, metallic particles, parts consisting of or containing a plastic material, particles of soil or dirt and/or other substance(s) which is or which are likely to adversely affect the appearance and/or the quality of the ultimate products. For example, a metallic particle is likely to puncture the web of wrapping material, and the same applies for particles of tobacco ribs, soil or the like. Therefore, it is advisable to segregate foreign matter from the main portion of the flow as expeditiously as possible, preferably well ahead of the location where the smokable material is draped into cigarette paper or the like.

The apparatus of FIG. 1 comprises a vibratory trough 4 which receives the flow 2 from a shredding machine or from a magazine (not shown) and advances the flow in a predetermined direction indicated by an arrow A. The trough 4 delivers successive increments of the flow 2 onto the upper reach of a first endless belt or band conveyor 6. The flow 2 contains particles of foreign matter at least a substantial percentage of which should be segregated from the useful (smokable) material as early as possible before it can adversely affect the appearance and/or quality of the rod-shaped smokers' products, e.g., the wrappers of plain or filter cigarettes, cigars or cigarillos and/or the taste of tobacco smoke.

The character 8 denotes in FIG. 1 a subdividing or segregating device which receives successive increments of the flow 2 from the conveyor 6 and segregates a stream 2 a (containing all or a major part of foreign matter) from a stream 2 b which is at least substantially devoid of foreign matter and is ready to be converted into the rod-like filler of a cigarette or the like. For example, the stream 2 a can contain 99% of foreign matter (i.e., of that foreign matter which was contained in the original flow 2), and the stream 2 b then contains at most 1% of the foreign matter originally contained in the flow 2. The exact details of the segregating device 8 which can be utilized in the improved apparatus form no part (or need not form part) of the instant invention. For example, such segregating device can include one or more laser detectors which scans or scan the flow 2 being supplied by the conveyor 6, a reference drum which is color-coordinated with tobacco, an optical scanner which is set up to detect the locations of foreign particles in the oncoming flow, as well as ejector means or expelling means (such as one or more nozzles) for physically segregating detected foreign particles from the satisfactory (major) part of the flow 2 being furnished by the conveyor 6.

It has been ascertained that one or more segregating devices 8, which can be employed with advantage to separate a high or very high percentage of foreign matter forming at least the major part of the stream 2 a, invariably segregate from the flow 2 a certain amount of smokable material (2 b) which, in the absence of any undertakings to the contrary, would be lost by being removed from the apparatus together with the segregated non-smokable material (including metallic particles, soil, fragments of tobacco ribs or the like). Otherwise stated, presently known segregating devices 8 are not likely to prevent segregation from the stream 2 b of a certain amount of satisfactory smokable material which, in the absence of any undertaking(s) to the contrary, is forced to leave the apparatus with the non-smokable material contained in the stream 2 a. A satisfactory segregating device 8 is likely or is expected to form (a) a first stream 2 b which contains about 99% of smokable material in the flow 2, and (b) a second stream 2 a which contains the remaining 1% of smokable material being furnished by the vibratory trough 4 and thereupon by the registering portion or section of the upper reach or stretch of the endless belt or band conveyor 6.

In accordance with a feature of the present invention, the segregating device 8 supplies the stream 2 a onto a second endless belt or band conveyor 10 which extends transversely of the direction indicated by the arrow A, i.e., transversely of the direction of transport of the flow 2 by the conveyor 6. The stream 2 b of smokable material is caused to descend or is otherwise transferred onto the upper reach of a third endless belt or band conveyor 14. The latter can be used to deliver satisfactory smokers' material (e.g., exclusively shreds of tobacco leaf laminae) to the machine (or to that part of a tobacco processing machine) which converts the stream 2 b into a continuous tobacco rod ready to be draped into one or more webs of cigarette paper or the like. The character 12 denotes in FIG. 1 a chute or an analogous device which is designed to direct the stream 2 b of satisfactory smokable material from the segregating device 8 and conveyor 10 onto the third conveyor 14.

The stream 2 b can be fed to a machine which makes a single tobacco rod or to a machine which simultaneously produces several tobacco rods. Commonly owned U.S. Pat. No. 5,072,742 (granted Dec. 17, 1991 to Heitmann for “METHOD OF AND APPARATUS FOR MAKING A FILLER OF SMOKABLE MATERIAL”) discloses a machine which is designed to produce a single continuous tobacco rod, and commonly owned U.S. Pat. No. 4,893,640 (granted Jan. 16, 1990 to Heitmann et al. for “MULTIPLE-ROD CIGARETTE MAKING MACHINE”) discloses a machine which is arranged to simultaneously produce a pair of continuous tobacco rods.

FIG. 2 shows that the discharge (right-hand) end of the upper reach of the conveyor 10 delivers successive increments of the stream 2 a toward the open upper end of a collecting receptacle 16 for disposable non-smokable material of the stream 2 a. In accordance with a further important feature of the present invention, the apparatus of FIGS. 1 and 2 further comprises an arrangement which serves as a means for pneumatically reintroducing, along a second path, at least some (2 aa) of the second stream 2 a into or along the first path (for the flow 2). Such reintroduction preferably takes place upstream of that (predetermined) portion of the first path where the flow 2 is subdivided into the streams 2 a and 2 b. The reintroducing arrangement comprises at least one suction gathering device 18 (e.g., a cup) which is installed above the upper end of the collecting receptacle 16 and serves to withdraw from the stream 2 a (at the discharge end 10 a of the conveyor 10) at least some particles of smokable material which is contained in the stream 2 a. The upper end of the suction gathering device 18 is connected with the intake end of a pneumatic conveyor 20 (shown in FIG. 2 in the form of an elongated conduit or hose or pipe). The device 18 lifts the relatively lightweight components of the stream 2 a, primarily or exclusively the shreds or analogous fragments of tobacco, but permits the heavier and/or bulkier particles of the stream 2 a to descend by gravity into the collecting receptacle 16 which is or which can be emptied at regular intervals or when necessary (e.g., when the receptacle 16 is filled up to a certain level).

The result is that the (third) stream 2 aa in the conduit 20 contains all or at least a very high percentage of smokable material which, in the absence of the pneumatic reintroducing means including the conduit 20, would be wasted by leaving the apparatus at 16, i.e., together with the non-smokable foreign matter which was randomly distributed in the flow 2 and constitutes the bulk of the stream 2 a on the conveyor 10.

The third stream 2 aa advances in the conduit 20 toward and into a gate or cyclon 22 having an outlet 24 leading (see the arrow 26) toward a suitable adjustable suction generating device (not shown). The cyclone 22 segregates the particles (mainly or exclusively tobacco and/or other smokable material) of the stream 2 aa from the body of air and discharges (at 4 b) the thus segregated particles into or onto a separate path or track 4 a which is adjacent one side of the trough 4 and conveys the received smokable material (stream 2 aa) onto the conveyor 6 whereon the material of the stream 2 aa advances in the direction of an arrow 6 a. (i.e., in at least substantial parallelism with the direction of the arrow A). The conveyor 6 can include two separate or at least partially separated sections, one for the flow 2 and the other for the stream 2 aa. In other words, the flow 2 passes through the segregating device or separator 8 only once but the material of the stream 2 aa passes through the device 8 once as part of the flow 2 and once as the discrete stream 2 aa which is caused to move in the direction indicated by the arrow 6 a. This ensures that the device 6 can separate from the stream 2 aa additional smokable material while the concentrated foreign matter descends and/or otherwise advances into an open-top (second) receptacle 28.

The aforementioned device 4 b can constitute a partition or wall which can be made of a metallic sheet material and segregates the flow 2 in the vibratory trough 4 from the stream 2 aa advancing toward and onto the endless belt conveyor 6. The receptacle 28 is or can be installed adjacent that end of the second conveyor 10 which is remote from the collecting receptacle 16 for more readily separable (such as heavier and/or bulkier) non-smokable material. That portion of smokable material which was part of the stream 2 aa but was segregated from the non-smokable material by the device 8 can be admitted directly to the stream 2 b or can reach the rod forming station along a separate path.

It has been ascertained that a highly satisfactory treatment of the flow 2 can be achieved if the receptacle 28 is arranged to receive about 30% of the stream 2 aa, i.e., that the improved apparatus can recover additional 0.7% of smokable material if the stream 2 b contains about 99% of smokable material. In other words, such apparatus can segregate from the flow 2 approximately 99.7% of smokable material which, at least in the long run, contributes significantly to the efficiency of segregation of non-smokable material from tobacco particles and/or particles of other smokable material.

An important advantage of the improved apparatus is that the component parts which are utilized to return the freshly segregated stream 2 a (consisting at least mainly of non-smokable material) into the flow 2 upstream of the segregating device 8 are more compact and simpler than the component parts in heretofore known apparatus. Another advantage of the improved apparatus is that the at least partially pneumatic constituents for the transport of the stream 2 a can be configurated and distributed in a manner which is best suited to ensure the assembly of a compact, lightweight and inexpensive apparatus which can be accommodated in the space that is available therefor in a modern high-speed machine for the making of rod-shaped smokers' products wherein the material of the rod-like filler originally contained a relatively high or a relatively low percentage of non-smokable material. For example, the pneumatic conveyor 20 can include or consist of one, two or more straight, arcuate and/or otherwise configurated metallic, plastic, textile or other sections.

The improved apparatus distinguishes from and constitutes a pronounced improvement over certain conventional apparatus which employ pneumatic collecting means for non-smokable materials. Reference may be had, for example, to WO 90/06065 A1 which discloses a suction generating device operating not unlike a vacuum cleaner and being arranged to draw particles of non-smokable material from a driven conveyor belt. The thus collected particles of non-smokable material (this term encompasses all such materials which should not be contained in the rod-like filler of a plain or filter cigarette or the like because it could adversely affect the taste and/or other characteristics of tobacco smoke and/or the mode of making such products) are gathered in a receptacle. This publication fails to suggest the utilization of pneumatic means for returning the stream containing at least the majority of non-smokable particles back into the original flow upstream of the locus or loci of segregation of non-smokable material from tobacco shreds and/or other desirable contents of a rod-like filler forming part of a cigarette or the like.

An advantage of the illustrated presently preferred embodiment of the improved apparatus is the simplicity of the arrangement which transports the stream 2 a from the downstream side of the segregating device 8 back to a location upstream of such device, e.g., and as shown in FIG. 1, back to a location upstream of the device 8. The suction cup 18 has an open underside which enables it to lift the lighter components (in 2 a) of the non-smokable material whereas the receptacle 16 collects the heavier non-smokable particles which cannot be entrained by the air stream in the tubular component 20 of the pneumatic conveyor. The suction cup 18 acts as a simple but highly reliable sifter or separator which segregates the lighter non-smokable material from heavier and/or bulkier particles of such material so that the latter can descend into the collecting receptacle 16 or into an equivalent thereof. The just described arrangement contributes to reliability, efficiency and versatility of the improved apparatus because the parts 8, 10, 16 and 18 cooperate to segregate non-smokable material from tobacco shreds and from other smokable material which is supplied by the flow 2, and the parts 16, 18 simultaneously cooperate to segregate heavier and/or bulkier non-smokable material from lighter and smaller particles of non-smokable material so that the heavier particles being gathered by the receptacle 16 need not share the movements of the particles forming the stream 2 a.

An advantage of the feature that the conveyor 10 is installed upstream of the pneumatic part of the transporting means for the non-smokable material is that the cup 18 of the pneumatic part can be oriented to face the oncoming material of the stream 2 a on the upper reach of the conveyor 10 and to lift the particles of the stream 2 a while the heavier and bulkier particles of non-smokable material simply descend from the discharge end 10 a of the conveyor 10, i.e., into the collecting receptacle 16.

The provision of the separate path (at 4 a) for the pneumatically returned stream 2 aa exhibits the advantage that the stream 2 a need not be thoroughly mixed with the entire (or with any) material of the flow 2 even though it can be treated by the segregating device 8 which divides the flow 2 into the streams 2 a and 2 b. Still further, the separate path 4 a renders it possible to ensure that the receptacle 28 can gather a high percentage of non-smokable material which was contained in the stream 2 aa. The receptacle 28 can constitute a simple container with an open top for admission of smaller particles of non-smokable material by gravity flow. The same applies for the receptacle 16; the discharge end 10 a of the conveyor 10 is located between the open top of the receptacle 16 and the open underside of the suction-operated gathering device 18 of the means (including the parts 18, 20, 22, 24 and 26) for pneumatically reintroducing at least some of the stream 2 a into the path defined in part by the pneumatic conveyor 20 and serving to advance the part 2 aa of the stream 2 a into the path for the flow 2 upstream of the conveyor 10.

A suitable flow dividing device 8 which can be utilized in the apparatus of FIGS. 1 and 2 is disclosed in WO 01/00333 A1 and U.S. Pat. No. 6,003,681 A.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of the above outlined contribution to the art of segregating foreign matter from comminuted smokable material and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the appended claims. 

1. Apparatus for segregating foreign matter which is randomly distributed in a flow of comminuted smokable material, comprising: means for advancing the flow in a predetermined direction along a first path; means for subdividing the flow, in a predetermined portion of said path, into a first stream which is at least substantially devoid of foreign matter and a second stream which contains at least a major part of foreign matter and is at least likely to contain some smokable material; and means for pneumatically reintroducing, along a second path, at least some of the second stream into said first path upstream of said predetermined portion of said first path.
 2. The apparatus of claim 1, wherein said reintroducing means comprises at least one tubular conveyor.
 3. The apparatus of claim 1, further comprising means for collecting the second stream downstream of said subdividing means, as seen in said predetermined direction, and means for segregating at least some foreign matter from said second path prior to reintroduction of at least some of said second stream into said first path.
 4. The apparatus of claim 3 for segregating relatively heavy foreign matter from lighter material, wherein said segregating means includes means for receiving the relatively heavy foreign matter by gravity flow and said reintroducing means includes a suction-operated gathering device for lighter material at said collecting means.
 5. The apparatus of claim 4, further comprising a conveyor extending at least substantially transversely of said predetermined direction downstream of said subdividing means and arranged to collect and advance the second stream, said conveyor having a discharge end at said segregating means.
 6. The apparatus of claim 5, wherein said discharge end is disposed at a level above said segregating means.
 7. The apparatus of claim 5, wherein said conveyor is an endless conveyor.
 8. The apparatus of claim 4, wherein said gathering device is arranged to draw lighter material from said second stream at said collecting means.
 9. The apparatus of claim 8, wherein said gathering device is disposed at a level above said segregating means.
 10. The apparatus of claim 1, further comprising a conveyor extending at least substantially transversely of said predetermined direction downstream of said subdividing means and arranged to collect the second stream.
 11. The apparatus of claim 10, wherein said conveyor is arranged to deliver the second stream to said reintroducing means.
 12. The apparatus of claim 10, wherein said conveyor includes an endless belt conveyor.
 13. The apparatus of claim 1, wherein said advancing means comprises a vibratory trough and an endless belt conveyor arranged to receive the flow from said trough.
 14. The apparatus of claim 1, wherein said advancing means comprises a track arranged to convey said at least some of the second stream to said subdividing means, said reintroducing means having an outlet arranged to discharge said at least some of said second stream into said track.
 15. The apparatus of claim 14, wherein said track includes a partition between said advancing means for the flow and said at least some of said second stream.
 16. The apparatus of claim 14, further comprising a receptacle arranged to receive said at least some of the second stream from said outlet of said reintroducing means.
 17. The apparatus of claim 16, wherein said receptacle has an open top for reception of at least some of the second stream. 